Operating internal combustion burners of the jet motor type



June 1957 P. F WINTERNITZ 2,794,316

OPERATING INTERNAL COMBUSTION BURNERS OF THE JET HQTOR TYPE Filed Feb. 23, 1949 DEPOSIT INVENTOR OPERATING INTERNAL CONIBUSTION BURNERS OF THE JET MOTOR TYPE Paul F. Winternitz, New York, N. Y., assignor to Reaction Motors, Inc., a corporation of New Jersey This invention relates to a novel internal combustion burner of the jet motor type and to a novel method of operating such a burner to prevent burn-out of the combustion chamber.

Jet motors have become of increasingly great importance in recent years. One of the difliculties facing the designers of such motors has been the tendency of their internal combustion chambers to burn out due to erosion and the high temperature of operation.

One object of the present invention is to provide a novel internal combustion burner of the jet motor type which is protected against premature burn-out. Another object is to provide a novel method for operating such a burner so that burn-out of the combustion chamber is prevented and the life of the motor is substantially extended.

The single figure of the drawing is a schematic, longitudinal, mid-sectional view of a jet motor which can be operated by the method of the invention.

In accordance with the present invention an internal combustion chamber is protected from burn-out by coating its inside surface with a refractory material which increases the life of the burner.

It has been observed that when the refractory coating is applied before operation of the burner it is effective for only a relatively short time and then substantially disappears from the chamber wall. This may be due to erosion, to vaporization of the coating due to the high temperature of the operation, and also to differential expansion between the chamber wall and the coating when a jet motor is started or stopped and a substantial temperature change takes place. T o overcome this difficulty, therefore, it is preferred to build up and maintain or renew the coating endogenously during operation of the combustion chamber. This is accomplished by continuously and concurrently injecting into the chamber an oxidant, such as liquid or gaseous oxygen, ozone, or peroxides, and a fluid fuel comprising a substance which burns in the oxidant to form a refractory solid material which is continuously deposited and built up or renewed on the internal wall of the chamber to maintain a protective coating thereon. The fluid fuel advantageously can comprise readily combustible organic and inorganic silicon compounds which burn in oxygen to form a refractory deposit of silica. Examples of such compounds are tetra ethyl orthosilicate, tetra methyl orthosilicate, trichlorosilane, dichlorosilane, and other combustible halogenated silanes or esters of orthosilicic acid or of their derivatives. A glassy protective coating of boron oxide is formed when the fluid fuel comprises diborane. A protective coating of aluminum oxide is obtained when the fuel comprises powdered aluminum.

In one specific example of how the method of the invention was performed, a water-cooled jet motor B was operated on a test block by introducing monomeric tetra ethyl orthosilicate through a supply conduit 11 to a header 13, from which it was discharged into an internal combustion chamber 15 through a plurality of injector Patented June 4, 1957 nozzles 17 arranged in a ring at one end of the chamber. At the same time oxygen was introduced through a supply conduit 19 and injected centrally into chamber 15 through an injector nozzle 21 arranged centrally within the ring of nozzles 17. At an oxygen-to-fuel ratio of .904 the motor was operated for several runs which lasted between 18.4 and 42 seconds, and in each run a protective coating 23 of silica was built up and maintained on the previously uncoated wall 25 of the combustion chamber, including the throat section 27. Motors having combustion chamber walls of both stainless steel and of graphite were operated in this way.

In a second series of tests a fuel consisting of high octane gasolene containing 30% of aluminum powder suspended therein was injected through the nozzles 17 while oxygen was injected through the nozzle 21. Upon conclusion of each run it was found that the previously uncoated wall 25 of the combustion chamber, including the throat 27, was coated with a protective layer 23 of aluminum oxide.

A third series of tests was made using diborane as the fuel. Runs were made with the diborane injected through the annularly arranged nozzles 17 and oxygen injected centrally through nozzle 21; and other runs were made with the diborane injected centrally through the nozzle 21 and the oxygen through the annularly arranged nozzles 17. With both arrangements at glassy refractory coating 23 of boron oxide was built up and maintained on the previously uncoated wall 25 of the combustion chamber, including the throat 27. However, it was observed that with diborane injected centrally the coating was practically all boron oxide, whereas with the reverse arrangement some free boron was present in the coating.

While specific embodiments of the novel method and apparatus have been described herein, for illustrating the principles of the invention, it is evident that changes in the method and apparatus can be made by persons skilled in the art, within the scope of the invention.

What is claimed is:

1. A method of operating and protecting from burnout an internal combustion burner of the jet motor type having a combustion chamber with internal walls including a convergent portion adjacent a discharge outlet subject to the erosive action of high temperature fast moving combustion products which method comprises externally cooling such internal walls with a coolant; continuously and concurrently injecting into said combustion chamber under pressure an oxidant and a fluid fuel comprising at least in part a substance which burns in such oxidant to form a refractory solid oxidation product; burning such fuel in said chamber at high temperature so that the gaseous combustion products are rapidly ejected from the combustion chamber between the convergent walls; and concurrently depositing, renewing and building up on said internal walls including the convergent portion a protective coating comprising portions of said refractory solid oxidation product, the amount of such substance in the fuel being at least sufficient to provide deposition at a rate to maintain and renew the protective coating on such internal walls and counteract said erosive action, said fluid fuel comprising a monomeric lower tetra alkyl orthosilicate.

2. A method of operating and protecting from burnout an internal combustion burner of the jet motor type having a combustion chamber with internal walls including a convergent portion adjacent a discharge outlet subject to the erosive action of high temperature fast moving combustion products which method comprises externally cooling such internal walls with a coolant; continuously and concurrently injecting into said combustion chamber under pressure an oxidant and a fluid fuel comprising at least in part a substance which burns in such oxidant to form a refractory solid oxidation product; burning such 1,405,482 Bostedo Feb. 7, 1922 fuel in said chamber at high temperature so that the gase- 1,888,749 Urquhart Nov. 22, 1932' ous combustion products are rapidly ejected from the 2,043,867 Rava June 9, 1936 combustion chamber between; theconvergent Walls; and 1 2,212,992 SOWa Aug. 27, 1940 concurrently depositing,.renewing and-building up iort said 5 2,257,194 Rosen Sept. 30, 1941 internal Walls including, theconvergent portion a pr'otec- 2,266,776 Leum Dec. 23, 1941 tive coating comprising portions'of said refractory solid" 2,268,589 Heany Jan. 6, 1942 oxidation product, thejamoun t of such,substance.,ini the, 2,272,342 Hyde Feb. 10, 1942 fuel being at least sufficient to. provide deposition at, a 2,399,687 McNabb May 7, 1946 rate to maintain and renew the protective'coatin'gon such 10 2,432,109 Zisman et a1 Dec. 9, 1947 internal walls and counteract said erosive action, said fluid 2,442,976 Heany June 8, 1948 fuel comprising monomerictetra ethyl orthosilicate, 2,558,483 Goddard June'26, 1951 2,563,305 Britton et a1. Aug. 7, 1951 References Cited in the file of this patent UNITED STATES PATENTS 15 FOREIGN PATENTS 1,167,135 Torsen Jan. 4, 1916 445,506 Great Britain Apr. 14, 1936 

